Interpretive Summary: Improving the processing quality of sugarbeet would enhance beet sugar’s competitiveness with cane sugar and alternative sweeteners. Amino-nitrogen is one of the naturally occurring constituents of sugarbeet, referred to as impurities, that interferes with the extraction of sugar during normal factory operations. Amino-nitrogen concentration is of special interest because of its direct relationship to nitrogen fertility management. This study examined the extent amino-nitrogen concentration could be altered by selection within a genetically diverse line and the impact selection for amino-nitrogen had on other components of processing quality. Four cycles of selection for low amino-nitrogen concentration resulted in a 29% reduction; whereas, selection for high amino-nitrogen concentration increased the concentration by 50%, compared to the parental source. The line selected for low amino-nitrogen concentration had higher concentrations of two other impurity components, sodium and potassium, and a lower sucrose loss to molasses than the line resulting from selection for high amino-nitrogen concentration. Selection for amino-nitrogen concentration, either high or low, did not have a detectable impact on sucrose concentration. However, root yield of the line selected for low amino-nitrogen was 9 Mg ha-1 greater than the root yield of the line selected for high concentration. Attempts to improve processing quality by selecting for individual impurity components will be complicated by interactions among the impurity components and environmental interactions.

Technical Abstract:
Improvements in sugarbeet (Beta vulgaris L.) processing quality, and therefore the cost-effectiveness of processing, will enhance beet sugar’s competitiveness with cane sugar and alternative sweeteners. Amino-nitrogen is one of the naturally occurring constituents of sugarbeet, referred to as impurities, that interferes with the extraction of crystallized sucrose during normal factory operations. Amino-nitrogen concentration is of special interest not only because of the relatively high weighting it receives in most formulas used to estimate the sucrose loss to molasses, but also because of its direct relationship to nitrogen fertility management. This study examined the extent amino-nitrogen concentration could be altered by selection within a broad-based germplasm line and the impact selection for amino-nitrogen had on other components of processing quality. Four cycles of mass selection for low amino-nitrogen concentration resulted in a 29% reduction; whereas, selection for high amino-nitrogen concentration increased the concentration by 50%, compared to the parental source. The line selected for low amino-nitrogen concentration had higher concentrations of two other impurity components, sodium and potassium, and a lower sucrose loss to molasses than the line resulting from selection for high amino-nitrogen concentration. Selection for amino-nitrogen concentration, either high or low, did not have a detectable impact on sucrose concentration. However, root yield of the line selected for low amino-nitrogen was 9 Mg ha-1 greater than the root yield of the line selected for high concentration. Attempts to improve processing quality by selecting for individual impurity components will be complicated by interactions among the impurity components and environmental interactions.